Thanks!
So, if this war broke out the Arapiles would be toast, but could perhaps do some damage before it was?
Arapiles would probably be boarded and taken by storm in port the minute war was declared, I'd assume. I don't know about how much damage it could do, but I'm getting a (historically) amusing mental image of the New York docks turning into a warzone if the Spanish are alert, resulting in the local militia bringing up artillery pieces to take on the trapped ironclad.

Realistically, though, it was in dry dock, so I don't see a seizure at gunpoint being resisted except with small arms fire.
Of course, a ledger of gun numbers etc doesn't take into account where the Spanish ships are going to be at the start of the war. Some presumably will be in Spain, and some probably at Manila. The former can get to Cuba before the US can take any potential advantage I expect
Best Regards
Grey Wolf
All of the other ironclads are in Spain at this point. The tricky part is that a rebellion at Spain's naval base in Valencia has just made large portions of the ironclad fleet ineffective due to the questionable loyalties of the crew, as well as the fact that at least one* has been blown up without her officers to run things.
That said, I determined that at least two ironclads at full strength,
Vitoria (the lone loyalist ironclad) and
Zaragosa (recaptured from the rebels in the fall of 1873, and given a loyalist crew), each by itself probably capable of smashing the American fleet at Key West, could be across the Atlantic by mid-January 1874. In a longer war, you could conceivably have every Spanish ironclad besides
Arapiles in the Caribbean by the summer of 1874.
*The
Tetuan. In my TL, war with America results in the cancellation of an anti-Carlist offensive in order to retake the ironclads at Valencia more quickly. This allows the seizure of the
Tetuan before it blows up like it did in OTL, allowing it to make the crossing under Rear-Admiral Chicarro in early 1874, albeit in an undermanned state.
EDIT: Errr...switch the notes on
Vitoria and
Zaragosa.
Zaragosa was the permanently-loyalist ship, etc.